1. Field of the Invention
The present invention relates to a shift actuator for multi-speed hubs on bicycles.
2. Description of the Related Art
A device for changing the transmission ratio of bicycles that has a pull rod passing through a hollow rear-wheel axle and a bell-crank lever that acts on the pull rod is disclosed in German Patent No. 436 419. The bell-crank lever is mounted in a carrier piece screwed onto the axle. A bearing eye of the bell-crank lever which surrounds a journal has a slot at the side to allow the bell-crank lever to be slid off the journal without releasing the journal.
Accordingly, this reference discloses a housing that is screwed onto the hub axle with a journal on which the bell-crank lever is mounted. The bell-crank lever is held in position on the journal by the forces that occur during actuation. Twist fitting without a tool is possible here as long as the bell-crank lever has been released from its actuating pull mechanism. After being unhooked from the linkage, the bell-crank lever is rotated out of the housing. Refitting is presumably more difficult inasmuch as the bell-crank lever has to be hooked back into the linkage.
The present invention is an axle shift device which comprises a housing with a pivoted lever arranged therein such that the pivoted lever is rotatable about a pivoting axis and can be displaced manually from the outside via a slide. The displacement via the slide enables the axle shift device to be selectively fitted on and removed from the hub axle for establishing and canceling a form-locking engagement with a force transmission element that is arranged in a central hole in a hub axle with the gear of the multi-speed hub for the purpose of changing the gear ratios.
The pivoted lever is connected to a remote control by a transmission component in the form of a wire. The remote control may be operated by the cyclist. The pivoted lever forms a structural unit with the transmission component that can be mounted on the cycle in a simple manner both when initially equipping the cycle and when repairing it. The structural unit may be preadjusted so that it is possible to prepare structural units for different types of hubs for mounting on the cycle without the requiring additional quality controls on the assembly line.
The force transmission element has a head and the pivot lever has a forked end which reaches the head. When the pivoted lever is actuated, the forked end pulls the head of the actuating element out of the multi-speed hub. A return spring ensures that when shifting back via the remote control, the force transmission element and the pivoted lever are pulled back into their original position. The slide in the housing of the axle shift device allows the axle shift device to be removed from the hub in any gear position of the axle shift device by releasing the form-locking connection between the forked end and the head of the force transmission device. The axle shift device may consequently be refitted if the slide is held in the disengaged position. When the slide is actuated, the forked end is preferably displaced parallel to the pivoting axis of the pivoted lever, with the result that the forked end moves away from the head and the form-locking engagement is cancelled. Once the form-locking engagement is cancelled, the axle shift device may be pulled off the hub axle. The technical solution just described should be regarded as one of several that are self-evidently possible structurally when it comes to the cancellation of the form-locking engagement. For example, the actuation of the slide may also be used to displace the pivoting axis in a direction perpendicular to the above-described direction of displacement, this likewise having the effect that the forked end is released from the head. It is furthermore conceivable for the forked end of the pivoted lever to be rotated or pivoted out of its form-locking engagement with the head or pushed out in some other way defined by one of the six degrees of freedom.
The axle shift device may optionally be arranged for holding the pivoted lever fast in the decoupling position after the latter has been decoupled from the force transmission element. In this optional embodiment, the axle shift device may always be fitted, both initially and in the case of a repair, merely by moving the slide into the decoupling position. It has been found that the best way of removing the axle shift device from the hub axle is for the force transmission element to be in a particular decoupling position, namely in the force-free state, relative to the multi-speed hub. In this state, the form-locking engagement between the forked end and the head may be made force-free by slackening the transmission component (i.e., in the form of a wire) such that it requires a minimum of manual actuating force to actuate the slide and thus decouple the pivoted lever. In this case, it is advisable to have a securing element to hold the pivoted lever in the position assumed during the decoupling process. The securing element may comprise a detent element that is arranged in the housing and acts on the slide. The release of the slide can be accomplished either by a return spring or by an additional manual actuating movement on the slide to bring about form-locking engagement once the axle shift device has been mounted on the hub axle.
It has been found expedient to incorporate a certain self-locking into the mountings of the slide to ensure that there is no feeding back of the shifting forces from the gear of the multi-speed hub into the coupling and decoupling process in the direction of the remote control. The shifting forces must thus pass from the remote control to the gear of the multi-speed hub, the forces or reaction forces that arise in the gear not being transmitted back in the opposite direction to the remote control via the transmission component in the form of a wire.
While previously it has been assumed that the axle shift device was held in position by the form-locking engagement of the pivoted lever with the head of the force transmission element, it is also possible to operate a gear of a multi-speed hub by a force transmission element moved by pressure by a pivoted lever. In this case, the slide activates or deactivates locking between the housing and the hub axle, this locking serving to secure the axle shift device on the hub axle.
Therefore, an object of the present invention is to provide an axle shift device that is removable from a hub axle of a multi-speed hub without tools. The axle shift device is connectable to a frame of a cycle as a structural unit in a simple manner both for initial fitting and for repair. A remote control for the axle shift device is connected via a transmission component in the form of a wire, i.e., a Bowden cable.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.